sin^(丌/4-a)+sin^2(丌/4+a)

sin^(丌/4-a)+sin^2(丌/4+a) sin^2(丌+a)= (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=? cosA+cos^2A=1,sin^2A+sin^4A+sin^8A (1-sin^6a-cos^6a)/(sin^2a-sin^4a) (1-sin^4a-cos^4)/(sin^2a-sin^4a) 化简 sin^4+sin^2cos^2+cos^2a= 化简:sin(3丌-a)/tan(a-5丌)x tan(-a+2丌)/cot(丌-a)x cos(4丌-a)/sin(-a-2丌) 【证明】Sin A+sin B=2Sin 22 化简［sin(2丌-a)-cos(11丌／2-a)］／［sin(-丌-a)sin(9丌／2+a)］ sin(arccos(2sin(a)))= 若sin^2a sin^2(-a)化简 已知sin(西塔+丌/4)=1/3,西塔∈(丌/2,丌),求sin西塔 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b sin a+sin 2a +sin 3a +...+sin na怎么求和? sin a+sin 2a +sin 3a +...+sin na怎么求和?